Occurrence, Sources, and Cancer Risk of Polycyclic Aromatic Hydrocarbons

in agricultural soil in China (Tao et al. 2004; Song et al. 2006; Wang et al. 2012; Zhu et al. doi:10.2489/jswc.71.4.327 2014). It is well known that PAHs and PCBs from contaminated soils could pose signif- icant risks to aquatic ecosystems, especially through surface run off and soil erosion (Luo Occurrence, sources, and cancer risk of et al. 2013). Hence, it is important to investigate the pollution of PAHs and PCBs in polycyclic aromatic hydrocarbons and agricultural soils near the Three Gorges Dam region, China. polychlorinated biphenyls in agricultural soils The objectives of this study were (1) to investigate the concentrations of PAHs and from the Three Gorges Dam region, China PCBs, (2) to identify the sources of PAHs and PCBs in agricultural soils, and (3) to M.X. Liu, Y.Y. Yang, X.Y. Yun, M.M. Zhang, and J. Wang evaluate the possible carcinogenic risk of PAHs and PCBs near the Three Gorges Abstract: Copyright © 2016 Soil and Water Conservation Society. All rights reserved.

Eighty agricultural topsoil samples were collected near the Three Gorges Dam Dam region, China. In addition, the study Journal of Soil and Water Conservation region of Yangtze River, China, to investigate concentrations, distribution patterns, and pos- could also provide useful information for sible sources and potential cancer risks of polycyclic aromatic hydrocarbons (PAHs) and agricultural soil management in the Three polychlorinated biphenyls (PCBs) in this area. Total PAHs concentrations in agricultural top- Gorges Dam region. soil ranged from 277.79 to 3,217.20 ng g–1 (ppb) with a mean concentration of 1,023.48 ± 815.31 ng g–1. Total concentrations of seven carcinogenic PAHs (C-PAHs) were between Materials and Methods 45.85 ng g–1 and 1,147.45 ng g–1, accounting for 6% to 49% of the total PAHs. Total PCBs Sample Collection. A total of 80 agricultural concentrations varied from 18.56 to 183.90 ng g–1 with a mean concentration of 35.28 ± topsoil samples were collected in March of 41.01 ng g–1. Positive linear correlations were found between total PAHs and total PCBs, 2013 at 16 sites near the Three Gorges Dam showing these compounds may originate from common sources. Isomer ratios analysis region along the Yangtze River (figure 1). indicated that atmospheric deposition was the main common source for PAHs and PCBs. Five 0 to 20 cm (0 to 7.87 in) subsamples The incremental lifetime cancer risk (ILCR) of PCBs in agricultural topsoil near the Three were randomly taken within a range of 200 –6 2 Gorges Dam region were all below 10 , indicating no cancer risk, whereas ILCR of PAHs m (2,153 ft) at each sampling site. All soil 71(4):327-334 were between 10–6 and 10–4; special attention needs to be paid to PAHs in the study area. samples were collected in agricultural fields. All samples were lyophilized, ground, and Key words: agricultural topsoil—polychlorinated biphenyls (PCBs)—polycyclic aromatic then passed through a 100-mesh (0.149 mm hydrocarbons (PAHs)—Three Gorges Dam region [0.006 in]) stainless steel sieve. Reagents and Standards. PAHs (1,000 mg www.swcs.org L–1 [ppm]) and PCBs (10 mg L–1) standard Polycyclic aromatic hydrocarbons (PAHs) pollution in soil and food (Faroon et al. solution were purchased from AccuStandard, and polychlorinated biphenyls (PCBs) are 2003). Soil is the primary steady reservoir for New Haven, Connecticut, United States. important and ubiquitous classes of per- PAHs and PCBs because PAHs and PCBs sistent organic pollutants. PAHs and PCBs are readily absorbed by organic matter in soil Min X. Liu is a PhD candidate in Key Laboratory can be found in the dust, soils, sediments, and hardly degrade (Wild and Jones 1995). of Aquatic Botany and Watershed Ecology of and atmospheric environment (Larsen and In addition, recycling of PAHs and PCBs Wuhan Botanical Garden, Chinese Academy Baker 2003). PAHs are of particular con- from contaminated soils into the atmosphere of Sciences, Wuhan, China, and University of cern, and 16 priority PAHs are regulated by is another pollution source to the environ- Chinese Academy of Sciences, Beijing, China. the US Environmental Protection Agency ment (Harner et al. 2001). Yu Y. Yang is an associate professor in Key Labo- ratory of Aquatic Botany and Watershed Ecology (USEPA). Several PAHs are known car- The Three Gorges Dam region is located of Wuhan Botanical Garden, Chinese Academy of cinogens, such asbenz[a]anthracene (BaA), from Badong County to Yichang City, Hubei Sciences, Wuhan, China. Xiao Y. Yun is a post- chrysene (Chr), benzo[b]fluoranthene Province, China, along the Yangtze River. graduate student in Key Laboratory of Aquatic (BbF), benzo[k]fluoranthene (BkF), benzo[a] Recently many reports on PAH and PCB Botany and Watershed Ecology of Wuhan Bo- pyrene (BaP), dibenz[a,h]anthracene (DBA), pollution of the Three Gorges Reservoir have tanical Garden, Chinese Academy of Sciences, and indeno[1,2,3-cd]pyrene (InP) (Ma et been published (Xu et al. 2007; Zhao et al. Wuhan, China, and University of Chinese Acade- my of Sciences, Beijing, China. Miao M. Zhang is al. 2009). Seven PCBs (PCB28, PCB52, 2007; Luo et al. 2010; Li et al. 2012). However, a research assistant in Key Laboratory of Aquatic PCB101, PCB118, PCB138, PCB153, these studies mainly focused on the persistent Botany and Watershed Ecology of Wuhan Bo- and PCB180) were defined as indicative organic pollutants of the water body, sedi- tanical Garden, Chinese Academy of Sciences, monomers by the United Nations GEMS/ ments, and water-level-fluctuating zone of the Wuhan, China. Jun Wang is a professor in Key Food (Food and Agricultural Organization Three Gorges Dam region; agricultural soils Laboratory of Aquatic Botany and Watershed of the United Nations Global Environment of this area were less noticed. In fact, serious Ecology of Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, China. Monitoring System) to monitor the PCBs pollution by PAHs and PCBs is often found

JOURNAL OF SOIL AND WATER CONSERVATION JULY/AUGUST 2016—VOL. 71, NO. 4 327 Figure 1 Map of sampling sites. PAHs standard solution includes acenaphthylene (Acy), acenaphthene (Ace), fluorene (Fl), phenanthrene (Phe), anthracene (Ant), fluoranthene (Flu), pyrene (Pyr), BaA, Chr, BbF, BkF, BaP, DBA, benzo[ghi]perylene P.R. China (BgP), and indeno[1,2,3-cd]pyrene (InP). PCBs standard solution includes PCB-28, Hubei Province PCB-52, PCB-101, PCB-118, PCB-153, PCB-138, and PCB-180. Dichloromethane and n-hexane are of chromatographic grade (Fisher Scientific, United States). Other S2 Badong County Yangtze River chemicals (carbon [C]18, anhydrous sodium S1 S3 sulfate [Na2SO4], and copper [Cu] powder) S4 are of analytical reagent grade. S6 Sample Extraction, Cleanup, and Analysis. S7 S8 S5 PAHs and PCBs were extracted following S9 S10

the modified matrix solid-phase dispersion Journal of Soil and Water Conservation extraction method (Rallis et al. 2012). Two S12 grams (0.07 oz) of soil samples were blended Three Gorges Dam S13 thoroughly with 3 g (0.1 oz) C as disper- Yichang 18 S14 City sion sorbent in a glass mortar for five minutes N using a glass pestle to obtain a homoge- S15 neous mixture. The mixture was completely transferred by using a funnel into a syringe S16 barrel-column (10 mL [0.34 oz]) with a 0.22 μm membrane filter. One gram (0.035 oz) of

anhydrous Na2SO4, 1 g of Florisil, 1 g of sil- ica gel, and 1 g of activated Cu powder were carrier gas at 1 mL min–1 (0.034 oz min–1) lyzed through the entire procedure prior to

placed into the column from bottom to top. under the constant flow mode. The injector and after every 10 samples. Each sample was 71(4):327-334 After the mixture was transferred into the and the detector were operated at 250°C and analyzed in triplicate. The average recoveries column, another membrane filter was added 300°C (482°F and 572°F), respectively. The of PAHs were 85% to 93% and PCBs were on the top of the column. The column was ion source and interface temperatures were 72% to 86%. The limits of detection (LODs) compressed with the syringe plunger for air set to 300°C and 280°C (536°F), respectively. of PAHs and PCBs were defined as three removal and then 20 mL (0.67 oz) dichloro- The GC oven temperature for PCBs times the signal-to-noise ratio (S/N). The www.swcs.org

methane (CH2Cl2) was used to elute the was programmed as follows: initial tem- LOD for PAHs ranged from 10 to 500 pg column. The eluent was collected into a con- perature was maintained at 70°C (158°F) g–1 and PCBs from 1 to 50 pg g–1, respec- ical tube. The extract was concentrated to 100 for two minutes and then programmed at tively. All the results were corrected for the

µL under a gentle high purity nitrogen (N) 25°C (45°F) min–1 to 150°C (302°F), at recoveries in this study. stream after 100 µL of isooctane was added 3°C (5.4°F) min–1 to 200°C (392°F), 8°C Cancer Risk Assessment. Incremental as solvent keeper. A known quantity of pen- (14.4°F) min–1 to 280°C (536°F), and hold- lifetime cancer risk (ILCR) was employed tachloronitrobenzene (PCNB) was added as ing the final temperature for 10 minutes. The to evaluate the potential risk for PAHs and an internal standard prior to gas chromato- GC oven temperature for PAHs was pro- PCBs in agricultural soils near the Three graph-mass spectrometer/electron capture grammed as follows: initial temperature was Gorges Dam region for human health based detection (GC-MS/ECD) analysis. maintained at 50°C (122°F) for 3 minutes on the USEPA standard models (USEPA Gas Chromatograph/Mass Spectrometer/ and then programmed at 10°C (18°F) min–1 1989; Chen and Liao 2006). The ILCRs for Electron Capture Detection Analysis. to 200°C, at 5°C (9°F) min–1 to 280°C, and adults through direct ingestion, dermal con- Qualitative and quantitative analysis was holding the final temperature for 10 minutes. tact, and inhalation were calculated using the carried out with an Agilent 7890A gas The data were acquired and processed with following equations (Peng et al. 2011): chromatography equipped with an elec- Chemstation software (Agilent, Santa Clara, 3 CS × CSFIngestion × BW/70 IRIngestion × EF × ED tron capture detector (GC-ECD) and a California, United States). , (1) ILCRsIngestion = 6 Model 5975 mass spectrometer (MS) using Quality Assurance and Quality Control. BW × AT × 10 electron-ionization ion source (EI) in the Average PAH and PCB recoveries and rel- CS × CSF × 3 BW/70 × SA × AF × ABS × EF × ED selected ion monitoring (SIM) mode. An ative standard deviations (RSDs) were first Dermal , and (2) ILCRsDermal = aliquot of 1 μL of the sample extracts was obtained to evaluate the method perfor- BW × AT × 106 automatically injected into an HP-5 capillary mance by multiple analyses of 10 soil samples CS × CSF × 3 BW/70 × IR × EF × ED column (30 m [98.4 ft] × 0.25 mm [0.01 in] spiked with PAHs and PCBs standards. A ILCRs = Inhalation Inhalation , (3) × 0.25 μm). Helium (He) gas was used as the solvent blank and matrix blank were ana- Inhalation BW × AT × PEF

328 JULY/AUGUST 2016—VOL. 71, NO. 4 JOURNAL OF SOIL AND WATER CONSERVATION Table 1 Concentrations of polycyclic aromatic hydrocarbons (PAHs) in agriculture topsoil samples near the Three Gorges Dam region (ng g–1). Compounds Type of PAHs TEF Mean Median Range SD 25% 75% Nap 2-rings 0.001 334.51 183.93 63.78 to 1,755.20 501.56 79.47 290.36 Acy 3-rings 0.001 1.51 1.16 0.21 to 6.42 1.44 0.86 1.55 Ace 3-rings 0.001 2.94 2.21 0.33 to 8.84 2.44 1.47 4.47 Fl 3-rings 0.001 46.28 46.04 2.28 to 80.01 17.78 34.99 56.20 Phe 3-rings 0.001 145.68 119.16 60.95 to 443.96 92.71 83.45 194.81 Ant 3-rings 0.01 135.28 110.47 55.99 to 414.39 86.75 77.10 181.25 Flu 4-rings 0.001 84.85 27.03 0.11 to 736.33 181.30 0.77 66.51 Pyr 4-rings 0.001 10.20 1.96 0.03 to 89.29 22.18 0.65 12.98 BaA 4-rings 0.1 3.99 3.96 3.94 to 4.26 0.10 3.94 4.05 Chr 4-rings 0.01 24.10 9.01 0.00 to 135.57 36.68 0.00 36.13 BbF 5-rings 0.1 6.09 6.04 6.01 to 6.78 0.19 6.01 6.06 BkF 5-rings 0.1 104.35 55.31 8.97 to 439.38 134.70 10.91 133.99 BaP 5-rings 1 62.22 14.65 4.72 to 576.08 141.82 5.20 40.57 DBA 5-rings 1 38.24 10.79 10.65 to 283.38 28.18 5.64 15.21 Copyright © 2016 Soil and Water Conservation Society. All rights reserved.

InP 6-rings 0.1 16.89 5.75 5.63 to 115.75 71.55 10.73 32.75 Journal of Soil and Water Conservation BgP 6-rings 0.01 6.34 7.22 0.00 to 7.33 2.48 7.21 7.27 Total C-PAHs 255.89 120.48 45.85 to 1,147.45 326.39 63.22 278.25 Total PAHs 1,023.48 623.97 277.79 to 3,217.20 815.31 461.39 1,706.56 Notes: TEF = toxic equivalency factor. Nap = naphthalene. Acy = acenaphthylene. Ace = acenaphthene. Fl = fluorine. Phe = phenanthrene. Ant = anthracene. Flu = fluoranthene. Pyr = pyrene. BaA = asbenz[a]anthracene. Chr = chrysene. BbF = benzo[b]fluoranthene. BkF = benzo[k]fluoranthene. BaP = benzo[a]pyrene. DBA = dibenz[a,h]anthracene. InP = indeno[1,2,3-cd]pyrene. BgP = benzo[ghi]perylene.

where CS is the sum of converted PAH samples. Total concentrations of the PAHs The contents of seven indicative PCBs are and PCB concentrations based on the toxic ranged from 277.79 to 3,217.20 ng g–1 with shown in table 1 and figure 2b. The highest equivalency factor (TEF) as shown in table a mean concentration of 1,023.48 ± 815.31 concentration of total PCBs was observed 71(4):327-334 1; CSF is carcinogenic slope factor ([mg kg–1 ng g–1. The higher concentrations (figure at sampling site S16 (183.9 ng g–1) and the –1 –1 d ] ; CSFIngestion, CSFDermal, and CSFInhalation 2a) of PAHs were observed at sampling sites lowest appeared at sampling site S1 (7.86 ng of PAHs were 7.3, 25, and 3.85 [mg kg–1 S4 (1,127.72 ng g–1), S11 (1,797.18 ng g–1), g–1). In general, PCB-52 showed the highest d–1]–1, respectively [Wang et al. 2007]; and S12 (2,134.33 ng g–1), S14 (1,706.56 ng g–1), concentration (18.56 ng g–1), accounting for –1 www.swcs.org CSFIngestion, CSFDermal, and CSFInhalation of PCBs S15 (1,149.15 ng g ), and S16 (3,217.20 53% of the total PCBs (figure 3b). PCB-153 were 2, 2, and 0.57 [mg kg–1 d–1]–1, respec- ng g–1), respectively. These sampling sites exhibited the lowest concentration (1.50 ng tively [USEPA 1997]); BW is body weight were located around different point pollu- g–1), accounting for 4% of the total PCBs. (kg; 70 kg [154.3 lb]); AT is the average life tion sources, such as the vehicle repair plant Cancer Risk Assessment. The total ILCR span (y; 70 y); EF is the exposure frequency (S4), gas station (S15), scenic spots (S11 and values of PAHs in agricultural topsoil near (d y–1; 350 d y–1); ED is the exposure dura- S12), and chemical plants (S16). Total con- the Three Gorges Dam region ranged –6 –4 tion (y; 30 y); IRIngestion is the soil intake rate centrations of PAHs in seven sampling sites between 10 and 10 with an average of (mg d–1; 0.001 mg d–1 [0.35 × 10–7 oz day–1]); (S1, S2, S3, S6, S8, S9, S10, and S13) were 10–5 (table 3), indicating a potential cancer 3 –1 3 –1 IRInhalation is the inhalation rate (m d ; 20 m below the median values of 623.97 ng g . risk. Generally, ILCR values higher than d–1 [5,283 gal day–1]); SA is the dermal sur- Concentrations of PAHs at S5 and S7 were 10–6 and 10–4 indicated a potential cancer risk face exposure (cm2 d–1; 5,000 cm2 day–1 [775 in a moderate level. (USEPA 1993). The cancer risk values of in2 d–1]); AF is the dermal adherence factor Seven PAHs( BaA, Chr, BaP, BbF, BkF, PAHs through ingestion and dermal contact (kg cm–2; 0.00001 kg cm–2 [0.1422 psi]); ABS InP, and DBA) are known as potentially ranged from 10–8 to 10–4 in all soil samples, is the dermal adsorption fraction (0.1); and C-PAHs, as it has been reported in several about 103 to 108 more than the cancer risk PEF is the particle emission factor (m3 kg–1; literatures (Sprovieri et al. 2007; Tian et al. level via inhalation, which varied from 10–12 1.32 × 109 m3 kg–1 [2.11 × 1010 ft3 lb–1]). 2013). As shown in figure 2a, total concen- to 10–11. This result was in accordance with trations of seven C-PAHs ranged from 45.85 the study of exposure to PAHs in urban sur- Results and Discussion to 1,147.45 ng g–1 with a mean concentra- face dust of Guangzhou (Wang et al. 2011). Polycyclic Aromatic Hydrocarbons and tion of 255.89 ± 326.39 ng g–1. Among the ILCR values of PCBs were all below Polychlorinated Biphenyls Concentrations. seven C-PAHs, BkF, accounting for 41% of 10–6 (table 3), indicating no potential can- Concentrations of PAHs and PCBs in all the total C-PAHs (figure 3a), showed the cer risk. For different exposure pathways, agricultural topsoil samples are presented in largest percentage, followed by BaP (24%), the increasing trend in cancer risks for PCBs table 1 and table 2. Sixteen priority PAHs DBA (15%), Chr (9%), InP (7%), BaA (2%), was as follows: ICLRDermal > ICLRIngestion > were all detected in agricultural topsoil and BbF (2%). ICLRInhalation.

JOURNAL OF SOIL AND WATER CONSERVATION JULY/AUGUST 2016—VOL. 71, NO. 4 329 Table 2 Concentrations of polychlorinated biphenyls (PCBs) in agriculture topsoil samples near the Three Gorges Dam region (ng g–1). Compounds Type of PCBs TEF Mean Median Range SD 25% 75% PCB-28 Tri-CBs 0.000002 4.82 2.36 0.42 to 43.22 10.28 1.58 2.99 PCB-52 Tetra-CBs 0.000005 18.56 10.95 2.55 to 126.20 29.30 6.82 17.00 PCB-101 Penta-CBs 0.00003 2.66 2.15 1.46 to 6.03 1.19 1.93 3.27 PCB-118 Penta-CBs 0.00003 2.39 2.44 0.49 to 4.63 1.20 1.48 3.30 PCB-138 Hexa-CBs 0.00001 2.95 1.85 0.23 to 15.32 3.69 0.88 4.12 PCB-153 Hexa-CBs 0.00002 1.50 1.31 0.16 to 4.54 1.36 0.37 1.91 PCB-180 Hepta-CBs 0.00001 2.39 0.24 0.07 to 12.76 3.95 0.19 2.75 Total PCBs 35.28 23.24 7.86 to 183.90 41.01 21.77 21.47 Notes: TEF = toxic equivalency factor.

Figure 2 Mean concentrations of (a) the carcinogenic polycyclic aromatic hydrocarbons (C-PAHs) and total PAHs and (b) total polychlorinated biphenyls

(PCBs) in the agricultural topsoil near the Three Gorges Dam region. Copyright © 2016 Soil and Water Conservation Society. All rights reserved. Journal of Soil and Water Conservation (a) 3,500 (b) 250 ) )

–1 3,000 –1 200 2,500 2,000 150

1,500 PCBs 100 1,000 PAHs and C-PAHs C-PAHs and PAHs 50 concentration (ng g concentration 500 (ng g concentration 71(4):327-334 0 0 S1 S2 S3 S4 S5 S6 S7 S8 S9 S10 S11 S12 S13 S14 S15 S16 Mean S1 S2 S3 S4 S5 S6 S7 S8 S9 S10 S11 S12 S13 S14 S15 S16 Mean Sampling sites Sampling sites

Legend www.swcs.org PAHs C-PAHs

Source Apportionment of Polycyclic and crude oil), between 0.4 and 0.5 implies study that combustion was the major con- Aromatic Hydrocarbons and Polychlorinated liquid fossil fuel combustion, and a ratio >0.5 tributor of the soils PAHs in Midway Atoll Biphenyls. Positive linear correlations were is the characteristic of biomass and coal com- (Yang et al. 2014). found between total PAHs and total C-PAHs bustion (Yunker et al. 2002). Principal component (PC) analysis has (r = 0.762; p < 0.01; figure 4a), total PAHs In the present study, the values of Ant/ been widely used to distinguish the pollut- and total PCBs (r = 0.737; p < 0.01; figure (Ant + Phe) ranged from 0.47 to 0.49 and ant sources (Liu et al. 2014). Three principal 4b), and total C-PAHs and total PCBs (r = Flu/(Flu + Pyr) values varied from 0.11 to components (PC1, PC2, and PC3) had been 0.670; p < 0.05; figure 4c). Therefore, PAHs 0.98, suggesting a mixed source of com- extracted with eigenvalues greater than one and PCBs in agricultural topsoil samples near bustion and traffic emission. Sources can and represented 78.46% of the total variance the Three Gorges Dam region may be from be classified into three distinct groups. As of PAHs in the agricultural topsoil samples. multiple sources. shown in figure 5, S8 and S9 exhibited the PC1 (table 4; 45.6% of total variances) asso- The isomer ratios of Ant/(Ant + Phe), typical characteristic of petrogenic sources. ciated with high molecular weight PAHs, BaA/(BaA + Chr), Flu/(Flu + Pyr), and S1 and S12 showed the signature of petro- including Phe, Ant, Ace, Flu, BkF, BaP, InP, InP/(InP + BgP ) were used to distinguish leum combustion (liquid fossil fuel, vehicle, Pyr, Chr, DBA, and BaA, which represented between petrogenic and pyrolytic sources and crude oil). The other 12 sampling sites the influence of diesel combustion. The die- (Zhang et al. 2006). The ratio of Ant/(Ant + suggested a source of biomass and coal sel emissions were characterized by Pyr, BaA, Phe) < 0.1 shows a petroleum source, while combustion. As a result, the primary PAHs Chr, BbF, BkF, InP, and DBA (Lee and Dong the ratio >0.1 indicates a combustion source. in the agricultural topsoil samples near the 2010; Hou et al. 2013; Wang et al. 2013). PC2 Furthermore, Flu/(Flu + Pyr) < 0.4 indicates Three Gorges Dam region can be thought (table 4) explained 20.11% of total PAHs and a petroleum source (liquid fossil fuel, vehicle, of as combustion. This result agreed with the indicated coal or biomass burning. Major

330 JULY/AUGUST 2016—VOL. 71, NO. 4 JOURNAL OF SOIL AND WATER CONSERVATION Figure 3 Percentage of individual congener of (a) carcinogenic polycyclic aromatic hydrocarbon (C-PAH) and (b) polychlorinated biphenyl (PCB).

(a) BkF, 41% (b) PCB52, 52%

BbF, 2%

Chr, 9% PCB28, 14%

BaA, 2%

PCB180, 7%

BaP, 24% PCB138, 8% InP, 7% PCB101, 8% PCB118, 7% compounds in PC2 were Phe, Acy, Ace, Fl, Ant, and BgP. Among them, Acy and Ace Table 3 are typically emitted from coal or fossil fuel Incremental lifetime cancer risks (ILCRs) assessment for polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). combustion (Khalili et al. 1995; Wang et al. 2013). Phe, Ace, and Ant were also associated Compounds ILCRsIngestion ILCRsDermal ILCRsInhalation Total ILCRs with PC1, suggesting that these compounds PAHs Minimum 2.96 × 10–08 5.07 × 10–06 2.37 × 10–12 5.10 × 10–6 71(4):327-334 not only derived from coal or fossil fuel Maximum 1.05 × 10–06 1.79 × 10–4 8.36 × 10–11 1.80 × 10–4 combustion, but also from diesel emission. Median 5.65 × 10–08 9.67 × 10–06 4.51 × 10–12 9.23 × 10–6 Overall, PC1 and PC2 related to petroleum Mean 5.65 × 10–08 3.10 × 10–05 1.45 × 10–11 3.12 × 10–5 combustion, regardless of the types of oil –13 –13 –12 –12 PCBs Minimum 6.20 × 10 3.10 × 10 3.54 × 10 4.47 × 10 www.swcs.org (gasoline, diesel, heavy oil, etc.). This result –12 –12 –11 –11 is in accordance with the consumption of Maximum 4.40 × 10 2.20 × 10 2.51 × 10 3.17 × 10 –12 –13 –12 –11 petroleum as an energy source. Thousands of Median 1.26 × 10 6.30 × 10 7.19 × 10 9.08 × 10 –12 –13 –12 –11 ships on the Yangtze River need lots of petro- Mean 1.51 × 10 7.54 × 10 8.60 × 10 1.09 × 10 leum as energy support. In addition, with the construction of the Three Gorges Dam, many tourists visit, and the increase in traffic cially at S16 (PCB-28 and PCB-52 accounted may originate from multiple source input. (number of vehicles) also enhances the PAHs for 91% of the total PCBs). In general, the The isomeric ratios analysis showed that pollution in the agricultural soils. This result low chlorinated PCBs were correlated with PAHs were likely derived from combustion can also explain why specific compounds papermaking progress and chemical plants of fossil fuels in this study area. PCBs mainly showed high levels at S4, S11, S12, S14, S15, wastewater discharge (Wang et al. 2005). originated from atmospheric deposition and and S16. Main pollutants at S4 were Phe, Ant, Considering the positive correlation between industrial waste. The present study provides and BkF; at S11, S12, and S15 were Phe and TOC and PCBs, atmospheric deposition and valuable PAH and PCB pollution records in Ant; at S14 were naphthalene (Nap), Phe, industrial wastewater discharge were the two the soil and a foundation for decision-making Ant, and Flu; and at S16 were Nap, Phe, Flu, sources for PCBs pollution. regarding PAH and PCB pollution in the soil. BkF, and BaP. PC3 contributed 12.75% of Some measures must be carried out to pre- the PAHs data with the highest loading from Summary and Conclusions vent further deterioration of the environment. Nap and BbF. Nap was recognized as a major The mean concentrations of PAHs and PCBs marker of coke production (Yang et al. 2010; in the agricultural topsoil samples near the Acknowledgements Wang et al. 2013). Three Gorges Dam region were 1,023.48 This project was supported in part by Open Funding PCB distribution profiles in the agricultural ng g–1 and 35.28 ng g–1, respectively. PAHs in Project of the Key Laboratory of Aquatic Botany and topsoil (figure 3b) showed that low chlo- this area had a potential cancer risk to human Watershed Ecology, Chinese Academy of Sciences, Natural rinated congeners (PCB-28 and PCB-52) health. Positive linear correlation between Science Foundation of Hubei Province of China (NO. accounted for 67% of the total PCBs, espe- PAHs and PCBs indicated these compounds

JOURNAL OF SOIL AND WATER CONSERVATION JULY/AUGUST 2016—VOL. 71, NO. 4 331 Figure 4 Positive correlation between (a) polycyclic aromatic hydrocarbons (PAHs) and carcinogenic polychlorinated biphenyls (C-PCBs), (b) PAHs and PCBs, and (c) C-PAHs and PCBs.

(a) 1,400 (b) 200 R = 0.76 R = 0.74 1,200 )

) 150

–1 1,000 –1 800 100 600 PCBs (ng g

C-PAHs (ng g C-PAHs 400 50 200

0 0 0 1,000 2,000 3,000 4,000 0 1,000 2,000 3,000 4,000

–1 –1

) 150 –1

100 PCBs (ng g 50 71(4):327-334 0 0 400 800 1,200 1,600 C-PAHs (ng g–1) www.swcs.org

2012FFB07301), and the Hundred Talents Program of the Khalili, N.R., P.A. Scheff, and T.M. Holsen. 1995. PAH sediment in Chongqing section of the Yangtze River. Chinese Academy of Sciences (Y329671K01). source fingerprints for coke ovens, diesel and, gasoline Environmental Science and Technology 33:1-5.

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332 JULY/AUGUST 2016—VOL. 71, NO. 4 JOURNAL OF SOIL AND WATER CONSERVATION Figure 5 The isomeric ratios of anthracene/(anthracene + phenanthrene) (Ant/[Ant + Phe]) versus fluoranthene/(fluoranthene + pyrene) (Flu/[Flu + Pyr]) in the agricultural topsoil samples. Song, Y.F., B.M. Wilke, X.Y. Song, P. Gong, Q.X. Zhou, 1.2 and G.F.Yang. 2006. Polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and heavy metals (HMs) as well as their genotoxicity in soil 1.0 after long-term wastewater irrigation. Chemosphere 65:1859-1868. Sprovieri, M., M.L. Feo, L. Prevedello, D.S. Manta, S. 0.8 Sammartino, S. Tamburrino, and E. Marsella. 2007. Heavy metals, polycyclic aromatic hydrocarbons and polychlorinated biphenyls in surface sediments of 0.6 the Naples harbour (southern Italy). Chemosphere 67:998-1009.

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Nap –0.09 –0.19 0.52 DC: US Environmental Protection Agency. 71(4):327-334 Acy –0.01 0.55 0.06 USEPA. 1997. Exposure Factors Handbook. Final Report. Washington, DC: Office of Research and Development. Ace 0.87 0.43 –0.13 Wang, Z., J. Chen, X. Qiao, P. Yang, F. Tian, and L. Fl 0.37 0.51 0.04 Huang. 2007. Distribution and sources of polycyclic Phe 0.75 0.52 0.09 www.swcs.org aromatic hydrocarbons from urban to rural soils: A case Ant 0.75 0.52 0.09 study in Dalian, China. Chemosphere 68:965-971. Flu 0.87 0.33 –0.17 Wang, W., M.J. Huang, Y. Kang, H.S. Wang, A.O. Leung, Pyr 0.63 –0.32 0.01 K.C. Cheung, and M.H. Wong. 2011. Polycyclic BaA 0.73 –0.62 0.15 aromatic hydrocarbons (PAHs) in urban surface dust of Chr 0.61 –0.61 –0.01 Guangzhou, China: Status, sources and human health BbF 0.04 –0.19 0.66 risk assessment. Science of the Total Environment 409:4519-4527. BkF 0.93 0.16 –0.16 Wang, Z., S. Huang, M. Ma, and Y. Wang.2005. Influences BaP 0.92 0.02 0.01 of dissolved organic carbon on the partitioning and DBA 0.88 –0.06 –0.14 bioconcentration oif polychlorinated biphenyls (PCBs) InP 0.74 –0.57 0.08 in Huaihe River. Acta Science Circumstantiae 25:39-44 BgP –0.42 0.71 –0.24 (in chinese). Eigenvalues 7.30 3.22 2.04 Wang, X.T., Y. Miao, Y. Zhang, Y.C. Li, M.H. Wu, and G.Yu. Variance (%) 45.60 20.11 12.75 2013. Polycyclic aromatic hydrocarbons (PAHs) in Cumulative (%) 45.60 65.71 78.46 urban soils of the megacity Shanghai: Occurrence, Notes: Nap = naphthalene. Acy = acenaphthylene. Ace = acenaphthene. Fl = fluorine. Phe = source apportionment and potential human health risk. phenanthrene. Ant = anthracene. Flu = fluoranthene. Pyr = pyrene. BaA = asbenz[a]anthracene. Science of the Total Environment 447:80-89. Chr = chrysene. BbF = benzo[b]fluoranthene. BkF = benzo[k]fluoranthene. BaP = benzo[a] Wang, Y., Z.J. Tian, H.L. Zhu, Z.N Cheng, M.L. Kang, C.L. pyrene. DBA = dibenz[a,h]anthracene. InP = indeno[1,2,3-cd]pyrene. BgP = benzo[ghi]perylene. Luo, J. Li, and G. Zhang. 2012. Polycyclic aromatic hydrocarbons (PAHs) in soils and vegetation near an e-waste recycling site in South China: Concentration, distribution, source, and risk assessment. Science of the Total Environment 439:187-193.

JOURNAL OF SOIL AND WATER CONSERVATION JULY/AUGUST 2016—VOL. 71, NO. 4 333 Wild, S.R., and K.C. Jones. 1995. Polynuclear aromatic hydrocarbons in the United Kingdom environment. A preliminary source inventory and budget. Environmental Pollution 88:91-108. Xu, C., W. Shu, C. Luo, and J. Cao. 2007. Water environmental health risk assessment of PAHs and PAEs in the Three Gorges Reservoir. Reserch of Environmental Science 20:57-60 (in chinese). Yang, J.M., A.G. Salmon, and M.A. Marty. 2010. Development of TEFs for PCB congeners by using an alternative biomarker—Thyroid hormone levels. Regulatory Toxicology and Pharmacology 56:225-236. Yang, Y., L.A.Woodward, Q.X. Li, and J.Wang. 2014. Concentrations, source and risk assessment of polycyclic aromatic hydrocarbons in soils from Midway Atoll, North Pacific Ocean. PLoS ONE 9:e86441. Copyright © 2016 Soil and Water Conservation Society. All rights reserved. Yunker, M.B., R.W. Macdonald, R. Vingarzan, R.H. Journal of Soil and Water Conservation Mitchell, D. Goyette, and S. Sylvestre. 2002. PAHs in the Fraser River basin: A critical appraisal of PAH ratios as indicators of PAH source and composition. Organic Geochemistry 33:489-515. Zhang, H., Y. Luo, M. Wong, Q. Zhao, and G. Zhang. 2006. Distributions and concentrations of PAHs in Hong Kong soils Environmental Pollution 141:107-114. Zhao, Q., Z. Guo, and X. Zhou. 2007. Research on the pollution of persistent organic pollutants in fish in Chongqing section of Three Gorges Reservoir. Sichuan Environment 26:14-16 (in chinese).

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